1. Field of the Invention
The present invention relates to an indexing plate for a time switch including slide contacts at the circumference of the indexing plate which are radially displaceable from an inoperative position to latch into at least one switching position, which incorporate an actuating projection and a switching finger opposite thereto, and which are conducted between the projection and the finger through slots in the indexing plate, wherein the switching fingers are spaced from each other at the circumference of the indexing plate and evidence a rim area and a switch edge, in whose path of movement there is located a switching element of a switch contact in the actuated or switching position.
2. Discussion of the Prior Art
An indexing plate of that type has become known from the disclosure of German Petty Pat. No. 76 27 289. In such an indexing plate, the contacting of the switching fingers is carried out below the indexing plate. The switching fingers freely overhang the indexing plate so as to be only slightly stiff because their narrow wall thickness. This leads to the result that appreciable tolerances or offsets can occur with regard to the switching timepoint.
In the indexing plate pursuant to the abovementioned German Petty Pat. No. 76 27 289 the switching fingers are contacted from below thereof. The switch edge of the switching fingers extends radially towards the indexing plate, in which the direction of displacement of the slide contacts lies perpendicular to the switching path of the switching element. A necessary constructional width of the switching element hereby requires a minimum lift for the displacement of the contact sliders, which cannot be reduced without further measures. An increase in the lift is also occasioned by a starting incline on the switching finger.
Furthermore, also disadvantageous in the indexing plate pursuant to the above-mentioned German Petty Pat. No. 76 27 289 is that a finally unavoidable impact or tolerances in the axial direction will change the manipulation of the switching element, which can also lead to offsettings in the provided switching timepoints.
The switching element in the German Petty Pat. No. 76 27 289 slides ahead of the slide contacts which are in their inoperative position over the open slots in the indexing plate. This increases the resistance to actuation.
In German Laid-open Patent Application No. 30 19 325 there is described an indexing plate for a time switch. In this prior art structure, the slide contacts are contacted in either an axial or radial direction. At contacting scanning in the radial direction, an axial play of the indexing plate becomes barely noticeable inasmuch as the switch edge is located axially parallel. In the arrangement pursuant to German OS No. 30 19 325, the slide contact does not possess any switching finger which would project through a slot in the indexing plate. The slide contact is conveyed between oppositely facing grooves of two rings. This leads to the result that every rotational displacement of the two rings relative to each other causes a clamping of the slide contacts. Since the grooves are at least partly outwardly open, any fouling or contamination will also lead to difficulties in the operating of the slide contacts.
It is particularly disadvantageous in the indexing plate pursuant to the above-mentioned German OS No. 30 19 325, that the switching element must be acted upon by the manipulating projections on the slide contacts, since thereby the switching element will, in every instance, be located within a region which must be held accessible for the user.